The OdbcDataAdapter serves as a bridge between a DataSet and data source for retrieving and saving data. The OdbcDataAdapter provides this bridge by using Fill to load data from the data source into the DataSet, and using Update to send changes made in the DataSet back to the data source.

When the OdbcDataAdapter fills a DataSet, it creates the required tables and columns for the returned data if they do not already exist. However, primary key information is not included in the implicitly created schema unless the MissingSchemaAction property is set to AddWithKey. You may also have the OdbcDataAdapter create the schema of the DataSet, including primary key information, before filling it with data using FillSchema. For more information, see Adding Existing Constraints to a DataSet.

Note

When you call the Fill method on a data source that does not have a primary key column, the OdbcDataAdapter tries to promote the unique constraint column to the primary key. In the process, the OdbcDataAdapter marks the unique constraint as not nullable. This behavior works unless there is a null value in the unique constraint column. If there is a null value, the Fill method fails with a constraint violation. To avoid this situation, do not allow null values in the unique constraint column.

Note

Due to the limitations of native ODBC drivers, only one DataTable is ever returned when you call FillSchema. This is true even when executing SQL batch statements from which multiple DataTable objects would be expected.